The present invention relates to an ultrasonic imaging appratus which can form an ultrasonic image in real time, enlarge or reduce the image and move the image on a display screen.
U.S. Ser. No. 852,793 discloses an apparatus which can form an ultrasonic tomogram, and move the tomogram on a display screen, and also can display an enlarged part of the tomogram on another screen while displaying the entire tomogram. This apparatus has an ultrasonic transducer. The transducer steers the region of interest (hereinafter called "ROI") with ultrasonic beams, thus obtaining image signals representing the tomogram. The image signals are stored in a frame memory for storing an entire image. The signals are read from frame memory and supplied to a display having two screens. The tomogram is displayed on the first screen. To enlarge and display a part of the tomogram, a cursor is moved on the first screen, thereby designating this part of the tomogram. Then, the ultrasonic transducer steers that part of the ROI which corresponds to the designated part of the tomogram, thus obtaining image signals representing the designated part of the tomogram. These signals are stored in a memory for storing an enlarged image. The signals are read from the memory and converted to enlarged image signals by a zooming process circuit. The enlarged image signals are input to the display, whereby the enlarged, designated part of the tomogram is displayed on the second screen.
The conventional ultrasonic imaging apparatus described above needs two signal-processing systems, one for processing signals to display the entire tomogram and the other for processing signals to display an enlarged part of the tomogram.